1. Field of the Invention
Exemplary embodiments of the present invention relate to a method for calibrating path characteristics of a transmitter and a receiver of a wireless spatial channel measurement apparatus such as a wireless channel sounder; and, more particularly, to a method for calibrating Tx/Rx path characteristics of a wireless spatial channel measurement apparatus using a multiple antenna.
2. Description of Related Art
Many studies have been in progress to develop a method for transmitting mess amount of data through a limited wireless channel in a next generation mobile communication system. As a result, many transmission methods have been introduced. In developing the next generation mobile communication system, it is required to accurately analyze characteristics of wireless spatial channels. Especially, it is required to analyze a wireless spatial channel in order to effectively apply a multi-antenna technology to the next generation mobile communication system.
For example, it is required to accurately estimate a wireless spatial channel to normally transmit data using the multi-antenna technology. In a mobile communication system for transmitting and receiving data using the multi-antenna technology, a transmitter transmits data through a wireless spatial channel by transforming a baseband signal to an intermediate frequency signal and transforming the intermediate frequency signal to a radio frequency signal (RF). A receiver receives data by transforming a RF signal transmitted through a wireless spatial channel to an intermediate frequency signal and transforming the intermediate frequency signal to a baseband signal.
As described above, it is required to transform a signal to a predetermined frequency band signal in order to transmit data through a wireless spatial channel using a multi-antenna technology in a mobile communication system. When the signal is transformed to the corresponding frequency band signal, the signal may be disadvantageously distorted. Also, the mobile communication system is disadvantageously required to have additional devices for transforming a signal to a corresponding frequency band signal. Accordingly, the complexity of a system may be increased.
A wireless spatial channel of a mobile communication system has a variable communication environment that varies in real time. Such a variable communication environment distorts a signal. Data transmission and reception performance depends not only on properties of multi-antenna transmitting and receiving data but also on characteristics of a wireless spatial channel. Therefore, it is required to accurately measure a wireless spatial channel and calibrate a path formed between a transmitter and a receiver based on the measurement result in order to transmit mess amount of data at a high speed through a limited wireless spatial channel using a multi-antenna technology in a wireless communication system.
That is, it is required to develop a method for minimizing distortion of a signal at a path formed between a transmitter and a receiver by accurately measuring a wireless spatial channel for transmitting data in a mobile communication system and for calibrating characteristic of a path of a transmitter and a receiver for minimizing the complexity of the system. In addition, it is required to develop a method for calibrating path characteristics by accurately and effectively measuring and analyzing characteristics of a wireless spatial channel for transmitting data in a mobile communication system and properties of a transmitter and a receiver, for example, properties of a plurality of transmission and reception antennas for transmitting data.